According to the almanac, there have been 988 shows since '99. I'll assume we can just say you'll be listening to 900 shows because maybe 88 or so (total guess) may not be accessible for whatever reason (Farm Aids, private shows, missing shows, etc).

How long is the average show...2.25 hoursish? That's over 2,000 hours of DMB listening time, better known as 84 days, or 12 weeks, or three months of straight listening.